1. Field of the Invention
The present invention relates generally to optical fiber devices and methods, and in particular to an improved all-in-one Raman fiber laser.
2. Background Art
Cascaded Raman fiber lasers (CRFLs) are useful devices for generating laser outputs at wavelengths at which rare-earth ionic gain is not available. A CRFL provides a stepwise transition from a starting wavelength to a selected target wavelength. The stepwise transition is created through cascaded lasing of one or multiple Raman orders in a suitable Raman gain medium. A nested series of Raman cavities are created in the gain medium by, for example, a corresponding nested series of in-line reflective grating pairs. Each successive cavity in the series is separated in wavelength from the preceding cavity by the respective Raman Stokes shift introduced by Raman scattering in the preceding cavity. A CRFL is typically pumped using a continuous-wave (CW) laser, such as a cladding-pumped Yb-doped fiber laser.
Raman fiber lasers are useful in a number of different applications, both at higher powers (e.g., greater than 20 W) and at lower powers (e.g., less than 10 W). However, because of their relative complexity, prior art Raman fiber lasers have a relatively high manufacturing cost. It is believed that, the cost issue is one reason that Raman fiber laser technology has not reached its full potential in the optical communications market.